The second-seeded former No. 1 got past gritty fourth-seeded Spaniard David
Ferrer 6-4, 7-6 (7-5) in a rematch of the 2007 final, which was also won by
the Swiss icon, in Shanghai.

Federer prevailed in 1 hour, 48 minutes by being broken only once on Day 4
against Ferrer, who owns an ATP-best seven titles this season.

The 31-year-old Federer has now reached at least the semis at this exclusive
event 10 times in 11 tries. He's seeking a third straight title in the elite
eight-player tournament, which he captured back-to-back in 2003 and 2004, 2006
and 2007, and the last two years.

Also on Thursday in London, sixth-seeded Juan Martin del Potro will battle
eighth-seeded Serb Janko Tipsarevic in more round-robin action at The O2
Arena.

Friday's round-robin play will pit top-ranked Australian Open champion Novak
Djokovic against fifth-seeded Tomas Berdych and world No. 3 U.S. Open and
Olympic titlist Andy Murray versus seventh-seeded Jo-Wilfried Tsonga. Djokovic
captured a Tour Finals title in 2008 in Shanghai, while del Potro was the
runner-up in 2009, and Tsonga was last year's runner-up to the amazing
Federer.

This week's four-player Group A features Djokovic (2-0), Murray (1-1), Berdych
(1-1) and Tsonga (0-2), while Group B boasts Federer (2-0), Ferrer
(1-1), del Potro (0-1) and Tipsarevic (0-1). The top-two players from
each group will play in the semifinals on Sunday, and the winners will
square off in the lucrative finale Monday in London.

The 2012 World Tour Finals champion can earn as much as $1.76 million.